微软.net精简框架常见问题及回答(中文版)(61)

王朝c#·作者佚名  2006-01-09
窄屏简体版  字體: |||超大  

6.15. Why do I get a MissingMethodException when I call a function from a native DLL?

There are several issues to consider when determining the case of a MissingMethodException. When this exception occurs you should verify the following:

If targeting Pocket PC 2003 use Microsoft eMbedded Visual C++ 4.0.

If targeting Pocket PC 2000 or 2002 use Microsoft eMbedded Visual Tools 3.0

Verify that the parameters to the function match those of the original

A long in native code is typically 32-bits, whereas in the .NET Compact Framework it is 64-bits

Beware of bool

According to MSDN documentation, "Its size is unspecified.":

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_vccelng4/html/ellrffundamentaltypes.asp

In a Microsoft specific section of the MSDN documentation, the bool size is described as varying depending on the version of Visual C++ used to build the binary.:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_vccelng4/html/ellrfbool.asp

A BOOL is defined as an int (32-bit value)

.NET Compact Framework Blittable Types:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_vccelng4/html/ellrffundamentaltypes.asp

Non Blittable Types and Marshaling Support:

http://msdn.microsoft.com/library/en-us/dv_evtuv/html/etconNonBlittableTypesMarshalingSupport.asp

Make sure that the function name is spelled correctly

Verify that the DLL is located correctly - Windows or executing folder of target device

Verify with DUMPBIN that the names of the functions were not mangled on exporting of the DLL (extern "C" fixes this). More information on this topic can be found in section "6.1. How do I call a function that is in a native DLL?" of this FAQ.

Verify that the DLL being imported is not dependant upon other DLLs. A missing dependant DLL will result in the MissingMethodException. For the latest Microsoft eMbedded Visual Tools and SDK downloads, visit the MSDN Mobile and Embedded Developer Center "Products & Updates" download page at:

http://msdn.microsoft.com/mobility/downloads/updates/default.aspx

6.16. How do I set the system time?

You can set the system time by P/Invoking the SetSystemTime function. //C#

using System.Runtime.InteropServices;

public struct SYSTEMTIME

{

public ushort wYear;

public ushort wMonth;

public ushort wDayOfWeek;

public ushort wDay;

public ushort wHour;

public ushort wMinute;

public ushort wSecond;

public ushort wMilliseconds;

}

[DllImport("coredll.dll")]

public extern static void GetSystemTime(ref SYSTEMTIME lpSystemTime);

[DllImport("coredll.dll")]

public extern static uint SetSystemTime(ref SYSTEMTIME lpSystemTime);

// Set the clock ahead one hour

SYSTEMTIME st = new SYSTEMTIME();

GetSystemTime(ref st);

st.wHour = (ushort)(st.wHour + 1 % 24);

SetSystemTime(ref st);

'VB

Imports System.Runtime.InteropServices

Public Structure SYSTEMTIME

Public wYear As UInt16

Public wMonth As UInt16

Public wDayOfWeek As UInt16

Public wDay As UInt16

Public wHour As UInt16

Public wMinute As UInt16

Public wSecond As UInt16

Public wMilliseconds As UInt16

End Structure

<DllImport("coredll.dll")> _

Public Shared Sub GetSystemTime(ByRef lpSystemTime As SYSTEMTIME)

End Sub

<DllImport("coredll.dll")> _

Public Shared Function SetSystemTime(ByRef lpSystemTime As SYSTEMTIME) As UInt32

End Function

'Set the clock ahead one hour

Dim st As New SYSTEMTIME

GetSystemTime(st)

st.wHour = Convert.ToUInt16(((Convert.ToInt32(st.wHour) + 1)) Mod 24)

SetSystemTime(st)

第一頁    上一頁    第61頁/共78頁    下一頁    最後頁
第01頁 第02頁 第03頁 第04頁 第05頁 第06頁 第07頁 第08頁 第09頁 第10頁 
第11頁 第12頁 第13頁 第14頁 第15頁 第16頁 第17頁 第18頁 第19頁 第20頁 
第21頁 第22頁 第23頁 第24頁 第25頁 第26頁 第27頁 第28頁 第29頁 第30頁 
第31頁 第32頁 第33頁 第34頁 第35頁 第36頁 第37頁 第38頁 第39頁 第40頁 
第41頁 第42頁 第43頁 第44頁 第45頁 第46頁 第47頁 第48頁 第49頁 第50頁 
第51頁 第52頁 第53頁 第54頁 第55頁 第56頁 第57頁 第58頁 第59頁 第60頁 
第61頁 第62頁 第63頁 第64頁 第65頁 第66頁 第67頁 第68頁 第69頁 第70頁 
第71頁 第72頁 第73頁 第74頁 第75頁 第76頁 第77頁 第78頁 
 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
 
 
© 2005- 王朝網路 版權所有 導航